Incorporation of visible light communication (“VLC”) capabilities into light emitting diode (“LED”) light fixtures is known. For example, light fixtures may be equipped with VLC capabilities that effectively convert the light fixtures into global positioning systems (“GPS”). Generally, light sources such as LEDs can be modulated (i.e., brightened and dimmed) at a high enough rate or frequency to be invisible to the human eye but detectible by a camera on a smart mobile device, such as a smartphone or tablet. The modulation appears to the camera as a pattern of light and dark lines, similar to a bar code, across the illuminated area of the modulating light source. A different modulation pattern may be used in each installed light fixture so as to create a unique bar code for each fixture, which ultimately can be manipulated into a unique identifier for each fixture. The light fixtures can then be used by a mobile device as a GPS that can, for example, direct the user to the desired area within a store in which the fixtures are installed.
Where long, linear light fixtures are used, it may not be desirable or necessary to modulate the light of all of the light sources within the fixture. Rather, only the light sources along a certain length (e.g., half) of the fixture may be modulated (referred to herein as the “VLC LEDs”), with the remaining light sources remaining un-modulated (referred to herein as the “non-VLC LEDs”). For example, the VLC LEDs may be provided on one LED array in the fixture and the non-VLC LEDS may be provided on an adjacent LED array in the fixture. However, in such situations the light emitted from the non-VLC LEDs may mix with the light emitted from the VLC LEDs, thus washing out the fidelity of the VLC LED light and rendering it difficult for the device to read the unique bar code for the fixture. There is a need for a device to help prevent such light contamination.